"Let me just tell you this Mitt "Muddle Mouth": I'm a single parent and my kids are *amazing*! Stick that in your magic underwear."

Faithful members of the Church of Jesus Christ of Latter-day Saints who receive temple ordinances wear an undergarment as a reminder of covenants they have made.

Charles Blow's tweets on Mormon undergarments

Blow was referring to a point in the debate where the candidates were discussing birth control, gay marriage and families. During the debate, Romney spoke of his belief that children were better off in homes with mothers and fathers.

On Friday, Blow issued the following apology via the same Twitter feed:

"Btw, the comment I made about Mormonism during Wed.'s debate was inappropriate, and I regret it. I'm willing to admit that with no caveats."

Blow has been a columnist for the New York Times since 2008, and has often been critical of conservatives.